How to count RecyclerView items with Espresso

问题

Using Espresso and Hamcrest,

How can I count items number available in a recyclerView?

Exemple: I would like check if 5 items are displaying in a specific RecyclerView (scrolling if necessary).

回答1:

Here an example ViewAssertion to check RecyclerView item count

public class RecyclerViewItemCountAssertion implements ViewAssertion {
  private final int expectedCount;

  public RecyclerViewItemCountAssertion(int expectedCount) {
    this.expectedCount = expectedCount;
  }

  @Override
  public void check(View view, NoMatchingViewException noViewFoundException) {
    if (noViewFoundException != null) {
        throw noViewFoundException;
    }

    RecyclerView recyclerView = (RecyclerView) view;
    RecyclerView.Adapter adapter = recyclerView.getAdapter();
    assertThat(adapter.getItemCount(), is(expectedCount));
  }
}

and then use this assertion

onView(withId(R.id.recyclerView)).check(new RecyclerViewItemCountAssertion(5));

I have started to write an library which should make testing more simple with espresso and uiautomator. This includes tooling for RecyclerView action and assertions. https://github.com/nenick/espresso-macchiato See for example EspRecyclerView with the method assertItemCountIs(int)

回答2:

Adding a bit of syntax sugar to the @Stephane's answer.

public class RecyclerViewItemCountAssertion implements ViewAssertion {
    private final Matcher<Integer> matcher;

    public static RecyclerViewItemCountAssertion withItemCount(int expectedCount) {
        return withItemCount(is(expectedCount));
    }

    public static RecyclerViewItemCountAssertion withItemCount(Matcher<Integer> matcher) {
        return new RecyclerViewItemCountAssertion(matcher);
    }

    private RecyclerViewItemCountAssertion(Matcher<Integer> matcher) {
        this.matcher = matcher;
    }

    @Override
    public void check(View view, NoMatchingViewException noViewFoundException) {
        if (noViewFoundException != null) {
            throw noViewFoundException;
        }

        RecyclerView recyclerView = (RecyclerView) view;
        RecyclerView.Adapter adapter = recyclerView.getAdapter();
        assertThat(adapter.getItemCount(), matcher);
    }
}

Usage:

    import static your.package.RecyclerViewItemCountAssertion.withItemCount;

    onView(withId(R.id.recyclerView)).check(withItemCount(5));
    onView(withId(R.id.recyclerView)).check(withItemCount(greaterThan(5)));
    onView(withId(R.id.recyclerView)).check(withItemCount(lessThan(5)));
    // ...

回答3:

To complete nenick answer and provide and little bit more flexible solution to also test if item cout is greaterThan, lessThan ...

public class RecyclerViewItemCountAssertion implements ViewAssertion {

    private final Matcher<Integer> matcher;

    public RecyclerViewItemCountAssertion(int expectedCount) {
        this.matcher = is(expectedCount);
    }

    public RecyclerViewItemCountAssertion(Matcher<Integer> matcher) {
        this.matcher = matcher;
    }

    @Override
    public void check(View view, NoMatchingViewException noViewFoundException) {
        if (noViewFoundException != null) {
            throw noViewFoundException;
        }

        RecyclerView recyclerView = (RecyclerView) view;
        RecyclerView.Adapter adapter = recyclerView.getAdapter();
        assertThat(adapter.getItemCount(), matcher);
    }

}

Usage:

onView(withId(R.id.recyclerView)).check(new RecyclerViewItemCountAssertion(5));
onView(withId(R.id.recyclerView)).check(new RecyclerViewItemCountAssertion(greaterThan(5));
onView(withId(R.id.recyclerView)).check(new RecyclerViewItemCountAssertion(lessThan(5));
// ...

回答4:

Based on @Sivakumar Kamichetty answer:

1. Variable 'COUNT' is accessed from within inner class, needs to be declared final.
2. Unnecessarily line: COUNT = 0;
3. Transfer COUNT variable to one element array.
4. Variable result is unnecessary.

Not nice, but works:

public static int getCountFromRecyclerView(@IdRes int RecyclerViewId) {
    final int[] COUNT = {0};
    Matcher matcher = new TypeSafeMatcher<View>() {
        @Override
        protected boolean matchesSafely(View item) {
            COUNT[0] = ((RecyclerView) item).getAdapter().getItemCount();
            return true;
        }
        @Override
        public void describeTo(Description description) {}
    };
    onView(allOf(withId(RecyclerViewId),isDisplayed())).check(matches(matcher));
    return COUNT[0];
}

回答5:

I used the below method to get the count of RecyclerView

public static int getCountFromRecyclerView(@IdRes int RecyclerViewId) {
int COUNT = 0;
        Matcher matcher = new TypeSafeMatcher<View>() {
            @Override
            protected boolean matchesSafely(View item) {
                COUNT = ((RecyclerView) item).getAdapter().getItemCount();
                return true;
            }
            @Override
            public void describeTo(Description description) {
            }
        };
        onView(allOf(withId(RecyclerViewId),isDisplayed())).check(matches(matcher));
        int result = COUNT;
            COUNT = 0;
        return result;
    }

Usage -

int itemsCount = getCountFromRecyclerView(R.id.RecyclerViewId);

Then perform assertions to check if the itemsCount is as expected

回答6:

You can create a custom BoundedMatcher:

object RecyclerViewMatchers {
    @JvmStatic
    fun hasItemCount(itemCount: Int): Matcher<View> {
        return object : BoundedMatcher<View, RecyclerView>(
            RecyclerView::class.java) {

            override fun describeTo(description: Description) {
                description.appendText("has $itemCount items")
            }

            override fun matchesSafely(view: RecyclerView): Boolean {
                return view.adapter.itemCount == itemCount
            }
        }
    }
}

And then use it like this:

onView(withId(R.id.recycler_view)).check(matches((hasItemCount(5))))

回答7:

Validated answer works but we can solve this problem with one line and without adapter awareness :

onView(withId(R.id.your_recycler_view_id)).check(matches(hasChildCount(2)))

Replace your_recycler_view_id with your id and 2 with the number to assert.

来源：https://stackoverflow.com/questions/36399787/how-to-count-recyclerview-items-with-espresso